A&P 5 lecture slides Flashcards
What is the Integumentary system is composed of and what do they contain
Cutaneous membrane (skin) with two layers
Accessory Structures: hair, nails, exocrine glands
Subcutaneous Layer: separates the integument above from the organs and muscles, composed of mostly adipose tissue
What are the two layers of Cutaneous membrane (skin)
Epidermis: superficial epithelium; “epi” above the dermis
Dermis: underlying layers of connective tissue
Function of the Integumentary system
Protection
Excretion
Maintenance of normal body temperature
Synthesis of vitamin D
Storage of nutrients
Sensory perception (touch, pressure, pain, temperature)
What is the epidermis composed of
stratified squamous epithelial tissue arranged in 4 to 5 layers, or strata
Features/functions of the epidermis
contains no blood vessels (avascular)
provides mechanical protection
prevents fluid loss
guards against microorganisms (e.g. bacteria, viruses)
What are the 5 layers of the epidermis from uppermost layer to the bottom layer
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum germinativum
Stratum germinativum features/functions
Bottom most (or basal) epithelial layer
Epidermal ridges increase the surface area of contact between epidermis and the underlying dermis
Basal (epithelial) cells produce new cells that replace lost or shed cells at surface
Melanocytes – produce melanin that colors epidermis
Merkel’s cells – cells sensitive to touch
Stratum corneum features
15-30 layers of dead flat epithelial cells that are filled with keratin
Keratinized cells are connected by desmosomes that hold them together ; cells shed in sheets
Skin Color contains variable quantities of 2 pigments: What are the colors of these pigments and vitamins associated with them
Carotene – yellow-orange pigment found in orange vegetables (carrots & squashes); can be converted into Vitamin A
Melanin – brown, yellow-brown or black pigment produced by melanocytes; melanin production is triggered by ultra-violet (UV) light from the sun; melanin protects from skin damage though some UV light is helpful for synthesizing Vitamin D)
Melanocyte cells are found where? What do they produce?
Found in stratum germinativum
Produce melanosomes, these travel to keratinocytes (epidermal cell which produces keratin) where they are broken down and release their pigment melanin
How can blood circulation color the skin?
Blood vessels travel in the dermis and in the tissue below the dermis
When blood is rich in oxygen, blood is bright red and this can influence skin color
When vessels are dilated, skin turns brighter red (e.g. blushing, heat, swollen)
But if blood is low in oxygen, the color of the skin becomes blueish (cyanosis); can appear blue around lips and beneath nails
Cyanosis can occur due
extreme cold, or in respiratory disorders, severe asthma, heart attack
Ultraviolet light stimulates epidermal cells in lower epidermis to synthesize
vitamin D
vitamin D3 (cholecalciferol)
this Vitamin D helps to promote
Calcium and phosphate uptake which keeps bones strong
Two Skin Cancers
Carcinomas- metastasis is rare; treatment is surgical removal of tumor
Melanoma- is more serious; cancerous cells grow rapidly & metastasize through the lymphatic system
Two types of Carcinoma skin cancer
basal cell carcinoma in stratum germinativum
squamous cell carcinoma higher levels of epidermis
Detection of Melanoma
Skin needs to be examined for unusual darkened spots that have:
Asymmetry – tend to be irregular in shape
Border – the border of a melanoma is unclear
Color – generally variable coloring in different areas (tan, brown, black, red, pink, white, blue)
Diameter – spot changes size. bigger than 5mm in diameter is dangerous
The Dermis connective tissue lying beneath the epidermis have two layers, what are the two layers called and what do they contain
Papillary layer consists of areolar tissue (loose connective tissue), capillaries, sensory neurons, various types of cells
Reticular layer contains interwoven meshwork of collagen & elastic fibers (irregular connective tissue) which enable it to withstand tension and physical distortion
What are they lines of cleavage
due to the orientation of bundles of collagen and elastic fibers in dermis
lines are oriented to resist stresses of movement
What are the clinical significance lines of cleavage
incision parallel to lines of cleavage heals quicker
incision perpendicular to lines of cleavage heals slower
Dermal Blood Supply function
Supplies blood to the hair follicles, sweat glands in the dermis
Sends small loops of capillaries to the dermal epidermal border
Nutrients diffuse into the epidermis
We find the subcutaneous plexus of small veins and arteries in
the hypodermis
Sensory receptors the epidermis contains
Merkel’s cells when touched release chemicals that stimulate nerve endings (Merkel’s discs), very sensitive to light touch
Free nerve endings unspecialized and respond to pain
Root hair plexus detect movement of hair
Sensory receptors the dermis contains
Meisner’s (tactile) corpuscles: light touch
Lamellated (pacinian) corpuscles: deep pressure; vibrations
Ruffini’s corpuscles: skin distortion
Subcutaneous Layer (hypodermis) consists of what and what is its function
Areolar & adipose connective tissue
Important in stabilizing the position of the skin relative to underlying muscles & organs
Contains a lot of venous blood, especially in upper part - the blood forms a “blood reservoir”, this blood can be shunted to general circulation (reservoir emptied and filled as needed)
The deep hypodermis has few blood vessels & no organs. This is a good site for to give injections (hypodermic needle)
Hair’s function
Protect scalp from ultraviolet light
Insulation
Guard entrances to nostrils, ear canals, eyelashes protect eyes
Hair roots are surrounded by sensory nerves (root hair plexus) can detect movement of shaft
Where is Hair produced in and composed of
Hair follicles
Composed of root and shaft
Hair’s root base are surrounded by
hair bulb & root hair plexus
What do hairs have
soft medulla & hard cortex
What is the hair cuticle
A protective layer of a hair (dead keratinized cells)
Four types of glands found in skin
Sebaceous glands
Sweat (sudoriferous) glands
Mammary glands
Ceruminous glands
Function of the Sebaceous (oil glands)
secrete oily, waxy sebum onto hair shaft; also found unassociated with hair on face, back, chest, nipples, external genitalia)
What are the two types of sweat glands, where they’re found and functions
Apocrine sweat glands – found in armpits, and groin; odorous secretion; usually associated with a hair
Eccrine sweat glands extensively found in skin, more watery type of sweat; cools surface of skin; excretes water and electrolytes (salt), dilutes harmful chemicals and kills microorganisms
Mammary glands are found where and what are is their function
glands found in breasts, secrete milk
Ceruminous glands are found where and what are is their function
deep in ear canal produce waxy cerumen
How many steps need to happen for skin to regenerate effectively
Four steps happen
What happens in step 1 of skin repair
bleeding occurs
scab is formed (from fibrin)
mast cells cause inflammatory response
What happens in step 2 of skin repair
scab isolates area
enhanced circulation
phagocytic cells active
fibroblasts move into area
stratum germinativum migrates under scab
What happens in step 3 of skin repair
scab is disappearing
fibroblast activity lead new tissue
What happens in step 4 of skin repair
scab is shed
epidermis is completed
newly formed scar tissue – inflexible, fibrous, noncellular
What tissue is the hair follicle composed of and where does it descend to
The hair follicle is made up of epidermis (epithelial tissue) that descends down into the dermis
